In plants, some microRNAs (miRNAs) can trigger the production of secondary small interfering RNAs (siRNAs) from their targets. miRNA-induced gene silencing (MIGS) exploits this unique feature to efficiently downregulate gene expression. The simple flanking of a sequence of interest with the target site for the miR173 (an miRNA able to trigger transitivity) is sufficient to start the production of secondary siRNAs and, consequently, silencing of the target gene. This technique can be easily adapted to promote gene silencing of more than one gene, even with those that share no sequence similarities. This chapter describes the necessary steps for designing and implementing the use of MIGS in plants.